Ouuughhh I can't really begin to comb the hundreds of chapters to give you an exact number, but it was during the "10 Years Later" arc, which was vol16 in the ~130 range....
It was a scene where Yamamoto essentially scolds Gokudera, that being loyal to/loving Tsuna exclusively, only puts the pressure on Tsuna & makes him essentially a burden. Chastises him for his exclusivity & obsessiveness.... so cartoonishly anti-Avvy sentiments. How dare you .....

It's such an out of pocket thing for Yamamoto of all people to say-- barring that it's 10 years later-- like, just a normal happy popular goodlooking boy Yama, to Gokudera, a bastard child born into the mafia, who is attached to Tsuna for saving his life ... it's such a meanass thing to say to someone who almost kills himself out of a sense of uselessness in previous arcs, like he doesn't need that, not how I'd get through to him... in a previous arc Tsuna has to basically talk him down from suicide by the temptation of getting to see fireworks together .... a better way to deal with Gokudera's issues ... give him a sense of value.... not .... call him a burden..... what kind of cruel sting... actually you're hurting the person you love most by loving them ...... what lizard wrote this .... ALSO,, IT'S THE.. STUPID MAFIA, THAT IS YOUR BOSS, IF HE'S THE RIGHT-HAND MAN THEN. YES HE SHOULD BE EXCLUSIVELY AND DOGGEDLY LOYAL TO Him,, i would say that is the entire godforsaken point... perhaps even a huge boon ... and as a kid raised around that stuff, those priorities make sense dude ... the talking cheese delivering a takedown out here... I've been mad about it for almost 20 years .... also just from a standpoint of what makes any character recognizable or amusing in a threadbare shounen with 200 characters and a new band of 7 every few months, what the fuck is Gokudera without the single-minded obsessive puppy behavior... why did we open this arc with him crying at Tsuna's grave ... of all things why would we even try to correct his way of being, and why would it be Yamamoto doing it, so inconsequentially in the middle of a very boring stupid fight with a nobody ... worse yet big win for the YamaGokus, my sworn nemesis... the fire burns in my soul to this day... the worlds most repugnant NOTP... in the days when that word meant something...

But like, Gokudera was always gonna be a joke n fodder, he's like just shitty & emotionally volatile, that's his archetype ... delinquent meme... Yamamoto would always be the author's idea of a good and honest boy... this kind of thing is er, exactly what JSHK is kind of healing me with, since it puts its stock shounen boy (Kou) thru the ringer... and is trying to teach him how to be insane...

Anyhoo. I liked the early shenanigans , the daily life arc stuff at the beginning, as a teen, but it's on the whole just a very worthless fodder schlock slop shounen, without much purpose or direction, you were right to not pick it up, and I can't even say Tsuna is likeable to me ffklgklfklhjk... but there will always be a cell in my brain going JUUUUUUDAIME!!!! JUUDAIME!!!! JUUDAIME!!!!!!!!!!!!!! . I think I was just a Gokudera kinnie before I knew that concept existed. out of my hands. and when I see him its like a very embarrassing middleschool photo of me. there can be no peace or serenity ... RIP ...